You need to format the disc in drive H: before you can use it

I get "you need to format the disc in drive H: before you can use it" message when trying to access an external eSata HD on my Windows 7 machine. The drive is a Sans Digital TR4M with 4 - 1TB drives config to Raid 5. It works fine on my Vista machine and XP machine. It also used to work on the Windows 7 machine.
Thanks
Jax

I have had issues in the past coming from XP and Vista machines that before unplugging a device if I didn't safely remove the device, Windows 7 wouldn't read it. This may not be the case for you but a suggestion never the less

thanks, I'm not sure how to procede though. I'm a phoographer who needs to archive images. I built the Sans Digital TR4M raid 5 with eSata for this purpose. It works fine on my XP & Vistas 64 machine but I get the error message on the Win 7 machine.